Do not define Avb_algorithm for autogen vendor boot partition

To align with the behavior of the make generated vendor boot partition.

Test: compare ninja commands
Bug: 379945468
Change-Id: I1d3c3829b5f3e1789469dff27b83f5ba2de1358c
diff --git a/fsgen/boot_imgs.go b/fsgen/boot_imgs.go
index 4e80720..c73c345 100644
--- a/fsgen/boot_imgs.go
+++ b/fsgen/boot_imgs.go
@@ -119,7 +119,6 @@
 			Avb_mode:           avbInfo.avbMode,
 			Avb_private_key:    avbInfo.avbkeyFilegroup,
 			Avb_rollback_index: avbInfo.avbRollbackIndex,
-			Avb_algorithm:      avbInfo.avbAlgorithm,
 			Dtb_prebuilt:       dtbPrebuilt,
 			Cmdline:            cmdline,
 			Bootconfig:         vendorBootConfigImg,